Sand production of oil wells is a difficult problem in exploitation a loose sandstone reservoirs, and it not only causes production reduction and production step of the oil wells easily and aggravates the attrition of ground and downhole equipment, but also results in sleeve damage and oil well abandoning in a serious case. It is reported in data that about 40% of oil wells need sand control all over the world, and this proportion is still increasing every year, this is because the mining intensity is higher and higher as the oil fields enter an ultra-high water cut development stage, the oil wells producing no sand originally start to produce sand, and the oil wells producing little sand originally start to produce a large amount of sand. How to effectively prevent and control the sand production of the oil wells is a research subject of petroleum exploitation countries.
Sand control is a main technical measure for solving the sand production problem of the oil wells, and about 80% of sand production oil wells all over the world adopt a mechanical sand control method at present, and the core component of mechanical sand control is a screen pipe. A slotted screen pipe is a most commonly used sand control tool in the oil fields at home and abroad at present, the slot shape of the slotted screen pipe is mostly rectangular, namely the slot width is uniform from outside to inside, and this screen pipe is liable to cause sand plug in the slot to reduce the oil production efficiency and shorten the service life of the screen pipe. A single trapezoidal slotted screen pipe can overcome the easy sand plug problem of the rectangular slotted screen pipe, but the slot thereof is easily expanded by the attrition of fine sand carried by crude oil, resulting in shortened valid period of sand control. A precise composite sand control pipe is well applied in oil wells with fine silt sand production, this screen pipe is composed of an inner aperture pipe, multiple layers of composite sand filtering screens and an outer protection pipe, the outer protection pipe and the multiple layers of composite sand filtering screens are welded on the inner aperture pipe, the deficiency lies in that the multiple layers of composite sand filtering screens are easily plugged by the fine sand carried by the crude oil to reduce the oil production efficiency, the plugging fine sand is difficult to scour and clean, the welds of the pipe bodies are liable to break when being used in thermal recovery oil wells, this screen pipe cannot automatically adjust the positions of the outer protection pipe, the multiple layers of composite sand filtering screens and the inner aperture pipe according to the stratum sand production and sand control conditions, and the controlled sand is liable to harden to reduce the production efficiency of the oil wells.
At present, no literature report on the movable combined sand control pipe of axial and radial slotted screen pipes is available at home and abroad.